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Tsz -Yam Lau and W. Randolph Franklin Rensselaer Polytechnic Institute

Improving river network completion under absence of height samples using geometry-based induced terrain approach. Tsz -Yam Lau and W. Randolph Franklin Rensselaer Polytechnic Institute partially supported by NSF grants CMMI-0835762 and IIS-1117277. Broader Impact.

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Tsz -Yam Lau and W. Randolph Franklin Rensselaer Polytechnic Institute

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  1. Improving river network completion under absence of height samples using geometry-based induced terrain approach Tsz-Yam Lau and W. Randolph Franklin Rensselaer Polytechnic Institute partially supported by NSF grants CMMI-0835762 and IIS-1117277 Autocarto 2012 Lau & Franklin

  2. Broader Impact • Better real-time monitoring of rapidly-changing hydrography with a huge set of aerial photographs captured from time to time Autocarto 2012 Lau & Franklin

  3. Contribution • Enhance the induced terrain approach with river segment geometry to further improve automated river reconnection accuracy Autocarto 2012 Lau & Franklin

  4. The induced terrain approach (Lau and Franklin, 2011) Autocarto 2012 Lau & Franklin

  5. Missing partial heights: obstacles Autocarto 2012 Lau & Franklin

  6. Missing partial heights: flat surface (LeFavor and Alsdorf , 2005) Amazon River basin-wide water-surface SRTM C-band heights (blue dots). A 3rd order polynomial fit of the data (green line) and with its slope (red line). Autocarto 2012 Lau & Franklin

  7. Baseline terrain model • V shapes centered at given river locations Autocarto 2012 Lau & Franklin

  8. Favoring shortest-path reconnections • A pair of river locations distant further apart has a higher cost to be connected. Known river locations x x x Autocarto 2012 Lau & Franklin

  9. Favoring shortest-path reconnections • A pair of river locations distant further apart has a higher cost to be connected. Difficult Easy x x x Autocarto 2012 Lau & Franklin

  10. Favoring shortest-path reconnections • Pros: Match human heuristics of linking segments with shortest length • Shortest length, lowest cost outlet outlet Autocarto 2012 Lau & Franklin

  11. Favoring shortest-path reconnections • Pros: Match human heuristics of linking segments with shortest length • Shortest length, lowest cost outlet outlet Autocarto 2012 Lau & Franklin

  12. Favoring shortest-path reconnections • Cons: Ignore “extend from tips” heuristic outlet outlet Autocarto 2012 Lau & Franklin

  13. Favoring shortest-path reconnections • Cons: Ignore “extend from tips” heuristic outlet Reconnection with baseline model outlet Autocarto 2012 Lau & Franklin

  14. Favoring shortest-path reconnections • Cons: Ignore “extend from tips” heuristic outlet Expected extension directions outlet Autocarto 2012 Lau & Franklin

  15. Favoring shortest-path reconnections • Cons: Ignore “extend from tips” heuristic outlet Expected reconnection outlet Autocarto 2012 Lau & Franklin

  16. Favoring shortest-path reconnections • Cons: Ignore “Join segments which faces each other” heuristic outlet outlet Autocarto 2012 Lau & Franklin

  17. Favoring shortest-path reconnections • Cons: Ignore “Join segments which faces each other” heuristic outlet Reconnection with baseline model outlet Autocarto 2012 Lau & Franklin

  18. Favoring shortest-path reconnections • Cons: Ignore “Join segments which faces each other” heuristic outlet Expected reconnection outlet Autocarto 2012 Lau & Franklin

  19. Favoring shortest-path reconnections • Cons: Ignore “replicate straightness behavior in the segment extension” heuristic outlet outlet Autocarto 2012 Lau & Franklin

  20. Favoring shortest-path reconnections • Cons: Ignore “replicate straightness behavior in the segment extension” heuristic outlet outlet Reconnection with baseline model Autocarto 2012 Lau & Franklin

  21. Favoring shortest-path reconnections • Cons: Ignore “replicate straightness behavior in the segment extension” heuristic outlet outlet Expected reconnection Autocarto 2012 Lau & Franklin

  22. Improvement • Reduce the rate of height increase at locations radiated from segment tips Autocarto 2012 Lau & Franklin

  23. Parameter setting:  • Determine the bending that we accept for privileged connections of mutually facing segments • Give good results with /4 or /8 on average. Autocarto 2012 Lau & Franklin

  24. Parameter setting: ’ • Control to what extent we favor height growing according to segment’s straightness over proximity to river locations • Give good results with 0.5  on average. Autocarto 2012 Lau & Franklin

  25. Results 40% of what we can correct with rich height samples (density = 10%) Autocarto 2012 Lau & Franklin

  26. Conclusion • Adjust the probability of receiving reconnection of different parts of the river segments • Shortest path is no longer the single criterion to determine how segments are reconnected • Recover 40% of what can be achieved with rich height samples (density = 10%) Autocarto 2012 Lau & Franklin

  27. Future work • Port the induced terrain framework to completion of 3D dendrite networks Autocarto 2012 Lau & Franklin

  28. Questions? 40% of what we can correct with rich height samples (density = 10%) Autocarto 2012 Lau & Franklin

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